Aircraft fuel tanks are typically composed of a structural container which surrounds an elastomer bladder. Such tanks typically include various access openings which are covered with bolted closures. In the design of such fuel tanks, one potential hazard is the potential for catastrophic failure due to foreign object impact damage and penetration of the fuel tank. It has been discovered that even using ballistic tolerant materials to produce the structural component of the fuel tank, it is possible that an object penetrating the tank wall at high velocity will generate a hydraulic pressure wave in the contained fluid. As the high speed object penetrates the tank and enters the fluid, it is slowed down due to drag forces. As it slows, the object transfers its kinetic energy to the surrounding fluid which generates an intense pressure wave. When this wave reaches the rigidly bolted closure, it is capable of producing catastrophic failure, stripping the bolts or fracturing the closure or surrounding structure. While additional strengthening bolts or other structures may be added to limit this type of failure, such structures add a severe weight penalty to the aircraft. Consequently, other means for avoiding instantaneous high pressure damage to closures on fuel tanks should be sought.